Multiple factors contribute to the matrix degradation observed in intervertebral disc disease. Among these, inflammatory and mechanical signaling pathways appear to play a significant role in maintaining the catabolic and anabolic balance of the disc matrix. It is the objective of this work to uncover how these critical pathways interact to result in net matrix breakdown or repair. Specifically, the aims of this research are to evaluate the response of intervertebral disc cells to inflammatory and mechanical stimuli and begin to unravel the pathways responsible for these effects. Preliminary data have demonstrated gene expression changes reflecting both protective and catabolic levels of both tension and compression, with duration of mechanical stimuli being the most significant factor in determining the cellular response. The proposed work will test the hypothesis that the protective effects of short duration mechanical stimulation against inflammatory stimuli will be reflected in decreased catabolic protein expression, activity and nuclear signaling. Similarly, we expect that catabolic protein expression, activity, and nuclear signaling caused by inflammatory stimulus will be exacerbated by prolonged mechanical stimulation. In addition, we expect that signaling through the nuclear factor kappa B (NFkB) pathway will be critical to these effects as it is involved in both inflammatory and mechanical signaling. We propose to utilize in vitro model systems to expose annulus fibrosus cells to tension and nucleus pulposus cells to compression as a starting point to examine the interaction of inflammatory and mechanical signaling pathways. We have chosen key outcomes measures which 1) have been shown to be important in disc matrix integrity;2) are affected by inflammatory and mechanical stimuli;and 3) demonstrated changes in their gene expression in response to the chosen loading regimens. These studies will provide insight into the biological significance of the previously observed gene expression changes, and uncover plausible mechanisms for the effects of inflammatory and mechanical stimuli on disc matrix homeostasis. It is anticipated that this work will lead to future studies examining the biologic outcomes of inflammatory and mechanical stimuli and the effects on disc degeneration. It is the long term goal of this work to identify key control points and synergy between the pathways which could potentially be exploited in future therapeutics. This would have profound impact by addressing the matrix integrity of intervertebral disc disease, which is critical in considering biological approaches to degenerative disc disease. PUBLIC HEALTH RELEVANCE: Low back pain is the second leading cause of patients seeking medical attention, and the highest reason for musculoskeletal related disability claims. Intervertebral disc degeneration and the associated biomechanical changes are among the most common causes of low back pain. Developing novel and more efficacious treatment options will require an improved understanding of the mechanisms involved in intervertebral disc degeneration, as outline in this proposal.